There are many situations in industry in which it is necessary to measure a parameter in the production process or in the surrounding environment. Process control and other control applications in industry often relies on sensors to provide feedback about the operating condition of equipment and processes. Large and complex Process Control systems or Supervisory Control and Data Acquisition (SCADA) systems have been developed for the purpose of automating processes and equipment in industrial and commercial plants. Such systems are typically not fully standardised but are often purpose built and usually include many proprietary devices and/or sub-systems, software and communication protocols.
However a drawback to the well known approach of gathering data for control purposes from sensors is that the cost of different such sensors, their installation, calibration, maintenance and eventual replacement represents a considerable investment and on-going expense.
The drive means for much of the equipment of a certain size in industrial and commercial is electric motors. Many electric motors used in industrial and commercial processes and buildings are controlled by soft starter equipment. Soft starters are used to start a motor and stop a motor in a desired manner, primarily to eliminate electrical current surges in the electrical supply and/or overheating in the motor. Soft starters are also used to reduce or eliminate mechanical shocks or vibration which might otherwise occur under start/stop conditions causing wear and damage to the pumps, fans etc. driven by the motors. A soft starter typically measures the input current of the motor and regulates the input current/and or voltage received by the motor to achieve a desired start or stop performance.
Soft starters are well known in general industrial practice, see for example, EP 1 037 373 A2, entitled “Command module for motor control system”.